74 IMMUNE SERA 



Inter-body and Complement. --We see, then, that 

 the haemolytic action of normal sera depends, just 

 as that of the specific hasmolytic sera, on the com- 

 bined action of two bodies: one, the inter-body, 

 which corresponds to the immune body of the 

 specific sera, and a second or complement. In 

 speaking of the constituents of normal serum, 

 Ehrlich and Morgenroth prefer to use this term 

 inter-body to distinguish it from the immune bodies 

 of specific haemolytic sera. 



Action not Entirely Specific. It has also been 

 found that there frequently exist normal sera which 

 are haemolytic not only for one species of red cell, 

 but for several. We saw, for instance, that normal 

 goat serum dissolved the red cells of guinea pigs 

 and rabbits. The question now arises, Is this prop- 

 erty of normal goat serum due to two inter-bodies 

 existing in the serum side by side, one fitting the 

 red cells of the guinea pig, the other those of the 

 rabbit? Ehrlich and Morgenroth answered this 

 in the affirmative, for in the following experi- 

 ment they succeeded in having each of the two 

 inter-bodies combine with its respective cell. To 

 some inactive normal goat serum they added rab- 

 bit blood and centrifuged the mixture. To the 

 separated clear fluid they again added some rab- 

 bit red cells as well as normal horse serum to reac- 

 tivate the mixture. Horse serum is not haemo- 

 lytic for rabbit red cells. The mixture remained 



